﻿EXDLicH.] 
  APPENDIX 
  ANCIENT 
  GLACIERS. 
  223 
  

  

  Ljell,* 
  following 
  the 
  view 
  of 
  Gastaldi, 
  considers 
  erratic 
  deposits 
  in 
  

   the 
  Miocene 
  formation 
  of 
  Turino 
  as 
  owing 
  their 
  present 
  position 
  to 
  gla- 
  

   cial 
  action. 
  By 
  Godwin- 
  Austen 
  deposits 
  in 
  the 
  Cretaceous 
  formation 
  of 
  

   England 
  are 
  claimed 
  as 
  having 
  had 
  a 
  similar 
  origin, 
  and 
  Escber 
  von 
  der 
  

   Linth, 
  considers 
  conglomeritic 
  accumulations 
  in 
  the 
  Cretaceous 
  of 
  Swit- 
  

   zerland 
  as 
  having 
  been 
  produced 
  by 
  glaciers. 
  A 
  number 
  of 
  English 
  

   geologists 
  have 
  even 
  asserted 
  that 
  a 
  breccia, 
  belonging 
  to 
  the 
  Permian 
  

   (at 
  Whitehaven) 
  formation, 
  could 
  not 
  have 
  been 
  deposited 
  by 
  anything 
  

   but 
  ice. 
  At 
  all 
  events, 
  explanations 
  of 
  this 
  kind 
  must 
  be 
  received 
  with 
  

   caution, 
  but 
  the 
  fact 
  of 
  such 
  comparatively 
  numerous 
  observations, 
  at 
  

   different 
  localities, 
  goes 
  far 
  to 
  show 
  that 
  the 
  assumption 
  of 
  the 
  existence 
  

   of 
  either 
  very 
  early 
  glacial 
  periods 
  or 
  very 
  early 
  local 
  glaciers 
  is 
  one 
  

   not 
  foreign 
  to 
  the 
  view's 
  of 
  a 
  geologist. 
  Nothing 
  that 
  I 
  can 
  conceive 
  

   of, 
  either 
  in 
  the 
  arrangement 
  of 
  the 
  conglomerate 
  or 
  in 
  its 
  correlation 
  

   with 
  neighboring 
  formations, 
  argues 
  against 
  the 
  conclusion 
  that 
  it 
  may 
  

   have 
  been 
  transported 
  to 
  its 
  present 
  place 
  of 
  deposition 
  by 
  the 
  action 
  

   of 
  moving 
  ice. 
  

  

  Considering 
  the 
  influence 
  that 
  ancient 
  glaciers 
  must 
  have 
  had 
  upon 
  

   the 
  configuration 
  of 
  San 
  Luis 
  Valley, 
  I 
  cannot 
  regard 
  it 
  as 
  having 
  been 
  

   other 
  than 
  subordinate. 
  Experience 
  has 
  shown 
  that 
  glaciers 
  will 
  follow 
  

   a 
  course 
  best 
  adapted 
  to 
  their 
  development, 
  and 
  that, 
  although 
  they 
  

   determine 
  in 
  a 
  very 
  large 
  measure 
  the 
  detail-features 
  of 
  the 
  region 
  they 
  

   traverse, 
  they 
  rarely 
  have 
  been 
  productive 
  of 
  radical 
  changes 
  extend- 
  

   ing 
  over 
  thousands 
  of 
  square 
  miles. 
  B. 
  v, 
  Cottaf 
  states 
  that 
  glaciers 
  

   certainly 
  have 
  no 
  opportunity 
  of 
  forming 
  unless 
  valleys 
  to 
  receive 
  

   them 
  already 
  exist.| 
  He 
  contends 
  that, 
  although 
  the 
  influence 
  of 
  mov- 
  

   ing 
  ice 
  upon 
  the 
  orographic 
  features 
  of 
  a 
  region 
  invaded 
  by 
  it 
  cannot 
  

   be 
  denied 
  or 
  overlooked, 
  it 
  has 
  heretofore 
  generally 
  been 
  overestimated. 
  

   It 
  is 
  possible 
  for 
  glaciers, 
  according 
  to 
  Cotta, 
  to 
  widen 
  valleys, 
  or 
  change 
  

   their 
  form 
  and 
  dimensions, 
  not, 
  however, 
  to 
  excavate 
  deep 
  fjords 
  or 
  val- 
  

   leys 
  at 
  places 
  where 
  such, 
  or 
  their 
  beginning, 
  never 
  before 
  existed. 
  A 
  

   case 
  corresponding 
  to 
  these 
  views 
  we 
  seem 
  to 
  have 
  in 
  San 
  Luis 
  Valley. 
  

   The 
  easterly 
  dip 
  of 
  the 
  volcanic 
  strata 
  west 
  of 
  the 
  valley, 
  and 
  the 
  ele- 
  

   vation 
  of 
  the 
  Sangre 
  de 
  Cristo 
  Eange, 
  together, 
  have, 
  in 
  my 
  opinion^ 
  

   produced 
  the 
  depression 
  of 
  San 
  Luis 
  Valley. 
  No 
  doubt 
  the 
  glaciers 
  

   near 
  its 
  border 
  had 
  a 
  very 
  considerable 
  influence 
  in 
  shaping 
  its 
  edges, 
  

   but 
  I 
  am 
  not 
  prepared 
  to 
  concede 
  that 
  the 
  entire 
  valley 
  was 
  covered 
  by 
  

   a 
  single 
  glacier, 
  or 
  that 
  the 
  entire 
  valley 
  owes 
  its 
  present 
  configuration 
  

   to 
  the 
  action 
  of 
  such 
  glacier. 
  Professor 
  Stevenson 
  says:§ 
  "The 
  whole 
  

   character 
  here 
  (Scm 
  Luis 
  Valley) 
  seems 
  to 
  admit 
  of 
  no 
  inference 
  other 
  

   ,than 
  that 
  the 
  valley 
  is 
  the 
  result 
  of 
  glacial 
  erosion." 
  For 
  the 
  reasons 
  

   above 
  given, 
  I 
  cannot 
  agree 
  with 
  this 
  " 
  inference 
  ", 
  as 
  it 
  seems 
  to 
  me 
  al- 
  

   together 
  too 
  much 
  at 
  variance 
  with 
  the 
  results 
  usually 
  produced 
  by 
  

  

  * 
  Principles 
  of 
  Geology, 
  I, 
  pp. 
  203 
  to 
  207. 
  

  

  tGeologie 
  der 
  Gegenwart, 
  1872, 
  p. 
  354. 
  

  

  t 
  Au 
  exception 
  to 
  this 
  rule 
  may 
  be 
  noted 
  as 
  occurriDg 
  in 
  the 
  regions 
  of 
  very 
  low 
  

   mean 
  annual 
  temperatures. 
  Dr. 
  Bessels, 
  of 
  the 
  Polaris 
  north 
  polar 
  expedition, 
  has 
  

   furnished 
  me 
  •with 
  the 
  following 
  data 
  regarding 
  the 
  formation 
  of 
  glaciers, 
  in 
  very 
  high 
  

   latitudes, 
  on 
  perfectly 
  level 
  table-lands. 
  In 
  case 
  the 
  temperature 
  of 
  the 
  warmer 
  sea- 
  

   sons 
  be 
  too 
  low 
  to 
  produce 
  a 
  melting 
  of 
  the 
  ice 
  and 
  snow 
  which 
  had 
  accumulated 
  

   during 
  the 
  cold 
  seasons, 
  the 
  formation 
  of 
  a 
  glacier 
  or 
  complex 
  of 
  glaciers 
  is 
  possible, 
  

   even 
  on 
  a 
  level 
  plateau, 
  which 
  contains 
  no 
  elevations 
  either 
  as 
  mountains 
  or 
  as 
  a 
  crest. 
  

   Cases 
  of 
  this 
  kiad 
  was 
  observed 
  by 
  Dr. 
  Bessels 
  on 
  both 
  sides 
  of 
  Petermann 
  Fjord, 
  

   north 
  of 
  north 
  latitude 
  80=^. 
  The 
  ice 
  then 
  has 
  a 
  motion 
  resulting 
  from 
  the 
  combined 
  

   effect 
  of 
  centrifugal 
  force 
  and 
  regelation. 
  This 
  case, 
  of 
  course, 
  can 
  only 
  occur 
  in 
  

   regions 
  where 
  we 
  have 
  arctic 
  climatal 
  conditions. 
  

  

  ^Eeport 
  Explorations 
  and 
  Surveys 
  West 
  One 
  Hundredth 
  Meridian, 
  1S75, 
  vol. 
  iii, 
  p. 
  

   460. 
  > 
  > 
  J 
  L 
  

  

  